Functional changes in mRNA expression and alternative pre-mRNA splicing associated with the effects of nutrition on apoptosis and spermatogenesis in the adult testis

Abstract

BackgroundThe effects of nutrition on testis mass in the sexually mature male have long been known, however, the cellular and molecular processes of the testis response to nutrition was not fully understood.MethodsWe tested whether the defects in spermatogenesis and increases in germ cell apoptosis in the testis that are induced by under-nutrition are associated with changes in mRNA expression and pre-mRNA alternative splicing using groups of 8 male sheep fed for a 10% increase or 10% decrease in body mass over 65 days.ResultsWe identified 2,243 mRNAs, including TP53 and Claudin 11, that were differentially expressed in testis from underfed and well-fed sheep (FDR < 0.1), and found that their expression changed in parallel with variations in germ cell numbers, testis size, and spermatogenesis. Furthermore, pairs of 269 mRNAs and 48 miRNAs were identified on the basis of target prediction. The regulatory effect of miRNAs on mRNA expression, in combination with functional analysis, suggests that these miRNAs are involved in abnormal reproductive morphology, apoptosis and male infertility. Nutrition did not affect the total number of alternative splicing events, but affected 206 alternative splicing events. A total of 159 genes, including CREM, SPATA6, and DDX4, were differentially spliced between dietary treatments, with functions related to RNA splicing and spermatogenesis. In addition, three gene modules were positively correlated with spermatogenesis-related phenotypic traits and negatively related to apoptosis-related phenotypic traits. Among these gene modules, seven (CFLAR, PTPRC, F2R, MAP3K1, EPHA7, APP, BCAP31) were also differentially expressed between nutritional treatments, indicating their potential as markers of spermatogenesis or apoptosis.ConclusionsOur findings on significant changes in mRNAs and pre-mRNA alternative splicing under-nutrition suggest that they may partly explain the disruption of spermatogenesis and the increase germ cell apoptosis. However, more research is required to verify their causal effects in regulating spermatogenesis and germ cell apoptosis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3385-8) contains supplementary material, which is available to authorized users.

Genome-wide association study to identify genomic regions and positional candidate genes associated with male fertility in beef cattle

“…Mitogen-activated protein kinase kinase kinase 1 (MAP3K1), was mapped within a window that explained 1% of the variance in SM (BTA20: 22.18-23.18 Mb) and was of interest for its anti-and pro-apoptotic functions in germ cells 36 . Guan et al 37 found the MAP3K1 gene was differentially expressed in testis from underfed and well-fed sexually mature sheep, indicating it could be a marker of germ cell apoptosis and therefore change SC and the efficiency of sperm production. The vasoactive intestinal peptide (VIP; BTA9: 89.51-90.51 Mb window), another prioritized candidate gene mapped within a window for SC that explained 1.61% of the variance, is known to act directly on the testis, promoting the production of testosterone in mice and rats 38,39 .…”

Enhancement of Germ Cell Apoptosis Induced by Chronic Ethanol in Transgenic Mice Overexpressing Fas Ligand

“…Apoptosis in testicular germ cells is critical for spermatogenesis in mammals (1,2). It is believed that apoptosis plays an important role in the removal of overproduced, genetically abnormal, or accidentally damaged germ cells.…”

Cellular and molecular responses of adult testis to changes in nutrition: novel insights from the sheep model

“…1). A total of 159 genes, including CREM and DDX4, were differentially spliced between dietary treatments, with functions related to RNA splicing and spermatogenesis (Guan et al 2017). Therefore, changes in alternative pre-mRNA splicing can help explain the effects on nutrition on spermatogenesis, but the effects of specific alternative types of splicing on spermatogenesis require further study.…”

“…In the testes affected by nutrition, we explored alternative splicing events using RNA-Seq and found that the alternatively spliced genes that differed between underfed and well-fed sheep were not related to apoptosis (Guan et al 2017), although one gene (HIPK3) was reported to be a member of a gene family that has been implicated in apoptosis. This result was surprising, because as indicated above, apoptosis is strongly associated with alternative splicing in other models in which nutrition was not the factor driving change in the testis.…”